It is flu season (or general sickness season) - so don't be too quick to blame the vape.
If you have been smoking a long time, maybe dual use for a while and cut back on the cigarettes instead of cutting them off completely. Either that, or just bear down and fight through the withdrawal symptoms for the next month or so (varies depending on the individual). There are a ton of other things in cigarettes which you crave other than nicotine. You are removing a lot of the toxins from your daily life, so your body is responding to that. I'm no doctor, just going based on what I've read, heard, and experienced (I was a light smoker - 1/2 PAD at my worst, not including rare occasion when I drank too much and killed a pack of smokes in an evening).
The easiest transition I've seen for a PAD smoker was cutting back to 3 cigarettes or so a day (first thing in the morning, after lunch and after dinner) for a month then down to 1 (the beloved morning cigarette with a cup of coffee was hard to kick). thats sort of a gradual step - still feeding your body those extra toxins enough to squelch most of the withdrawal symptoms. It seems like its about 1-2 months after you quit completely when you notice the biggest effect on your lungs and senses. theres an "ah-ha!" moment in there where your like, "Man, I can breath better and this juice tastes DELICIOUS!" ... the worst part for me quitting smoking was smelling all the nasty crap... seemed like most of the time I wished I still smoked because the foul smells where always so much more pungent then the present smelling things. Time cures all though, now I don't feel that way - I enjoy my sense of smell more now, finding pleasant smells much more often and just as pungent as the foul smells.
As others have said - drown your self with water! seriously, drink a ton - always have water with you and drink every time your feel dry mouth or thirsty.